. >> reporter: the companies argue the national security agency is going too far in the bulk collection of phone and internet data. dnformation from classified documents leaked by edward snowden suggest the n.s.a. is stealing communications from internet providers by tapping into cables connecting the servers in overseas data centers. in today's letter, the tech firm said they are now tightening internal cyber security. "we are focused on keeping users' data secure, deploying the latest encryption technology to prevent unauthorized surveillance." the tech firms are also fighting back against surveillance which is authorized. internet companies say courts too often are compelling them turn over potentially sensitive customer data. now, the u.s.-based firms are worried that all of this is bad for business. scott, the yahoo! chief in fact says massive government snooping has shaken the trust of users. >> pelley: bad for business, good for p.r. bob orr in our washington newsroom. thank you, bob. a top university took action today to stop an outbreak of meningitis. a new cancer treatment use